Soon it was discovered that the only real drawback of the VIIA was the small fuel storage for the role intended. This was mostly fixed in the VIIB which had additional 33 tons of fuel in external saddle tanks which
gave them additional range of about 2500nm at 10 knots. They were also considerably more powerful and slightly faster than the VIIA was. These boats (and all following the design) had two rudders instead
of the one found on the VIIA. This gave them even more agility.

These boats had the same armament as the VIIA, 4 bow torpedo tubes and one tube at the stern. U-83 was the only type VIIB without the stern torpedo tube. The only major armament difference was that 3 additional torpedoes could be stored for a total of 14. The next development
of these series was the mass produced type VIIC with several improvements.

Type VIIB included many of the most famous U-boats during World
War 2, including Kretschmer'sU-99, U-48 which was
the most successful U-boat, Prien'sU-47 and Schepke'sU-100.